Storage system for granular materials

ABSTRACT

A storage system for large quantities of flowable, granular materials, such as grain. The material is covered by flexible cover sections which are spread out on an impervious support surface and thereafter laced together to define a cover having a centrally located opening. The cover is grasped in the region of the central opening and lifted to a predetermined fill height; the perimeter of the cover being free to pull inwardly as necessary accommodating the lifting. Thereafter, the granular product is introduced into the opening until it reaches the predetermined fill height and defines a pile extending downwardly toward the support surface along a natural angle of repose. As the pile grows, it raises the cover while sweeping it upward away from the center of the pile. By this means the entire finished pile is conformably covered by the cover. After the pile has been established in its final configuration, the perimeter of the cover is fastened down, preferably to a retaining wall surrounding the base of the pile.

BACKGROUND OF THE INVENTION

The present invention relates to a system for storing flowable, granularmaterials, such as grain in large piles which may contain as much asthree million bushels of the materials.

Granular materials, such as grain, are generally stored in largecommercial elevators or in other permanent structures. During harvestingseasons such permanent storage facilities often times become filled andother storage facilities must be found. Sometimes the grain must be leftin the open in uncovered piles thereby causing serious loss due to theelements. Other times the excess grain is stored in small temporaryfacilities, which may be of either rigid or collapsible construction.Typical examples of collapsible storage facilities are shown in GardonU.S. Pat. No. 1,473,845, Wunderwald et al U.S. Pat. No. 2,730,150,Bronner U.S. Pat. No. 3,539,057, Luders U.S. Pat. No. 3,727,656, andPtaszek U.S. Pat. No. 4,121,389.

Wunderwald and Luders both show systems where grain is piled under aflexible cover in supporting relation thereto. The covers have a centralopening and are initially in a collapsed condition. The central openingis lifted, and grain is introduced therethrough to form a pile whichextends downwardly from the fill point along a natural angle of repose.This angle may be in the order of about 27° for wheat or 22° for corn.

Wunderwald's system includes a flexible bottom portion which is attachedto the cover, and the bin which is so defined is secured in place bystaking down the margins prior to filling. In the system of Luders thecover is positioned upon an impermeable base. The edges of the cover arejoined to the periphery of the base by an adhesive or by heat sealing.Alternatively, the cover is formed integral with the base.

The systems of Wunderwald and Luders both are limited to use for storingrelatively small quantities of grain in the order of about 1,000 bushelsor less. When the teachings of Wunderwald or Luders are extended tolarger size storage operations it is found that the filling opening inthe cover cannot be lifted to proper fill height due to the naturalsagging of the cover material. For example, a 25,000 bushel pile of cornhas a height of about 17 ft. and a diameter of about 84 ft. at the base.The surface area requiring coverage by the cover is about 600 sq. yd.,and a suitable cover material for such an area weights over 700 lbs.

Accordingly, it may be appreciated that there has been a need for areadily erectable temporary storage facility for large quantities offlowable granular materials.

SUMMARY OF THE INVENTION

The present invention provides a method and system for storage offlowable granular materials in large piles, preferably larger than about25,000 bushels up to about 3,000,000 bushels. In the method according tothis invention a plurality of mating, flexible and impervious coversections are positioned upon a suitable support surface and securedtogether to define a cover having a centrally located opening; the outerperimeter of the cover being free to move. After the cover has beenassembled, it is grasped in the region of the central opening and liftedto a predetermined fill height. When the lifting has been completed, thecover sags arcuately downward in a typical catenary curve with theperimeter being pulled inwardly as necessary to accommodate suchcurvature. Once the cover has been lifted to the predetermined fillheight, the granular product is introduced into the opening and filledto define a pile of the desired size. As the pile grows it raises thecover and also carries it outwardly. When filling has been completed thecover is supported by and conformably covers the entire pile. The piledefines a cone with its peak at the fill point. The surface of the pileextends downwardly from the peak at an angle of repose which is normalfor the material being piled.

The system which is produced by the method of this invention includesthe supporting surface with the granular material piled thereon andcovered by the assembled cover. The system also preferably includes aretaining wall around the base of the pile and an aeration towerextending upwardly through the pile from the support surface to the peakthereof. The cover may be attached to the aeration tower and to theretaining wall.

Accordingly, it is an object of this invention to provide an improvedmethod for storing a flowable granular material and a storage systemresulting therefrom.

Other and further objects of the invention will be apparent from theattached drawings, the following specification and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side elevation view of a storage system in accordance withthis invention;

FIG. 2 is a horizontal plan view of the system of FIG. 1;

FIG. 3 is a pictorial illustration of a portion of a support surface,retaining wall and aeration tower for use in practicing the presentinvention;

FIG. 4 is a pictorial illustration of a portion of a retaining wall, asviewed from the rear side thereof;

FIG. 5 is a pictorial illustration of the step of placing a coversection upon the support surface of this invention;

FIG. 6(a) is a sectioned end view of a cover seam;

FIG. 6(b) is a plan view of a cover seam;

FIG. 7 is a pictorial illustration of a cover being lifted by a liftingring;

FIG. 8 is a pictorial illustration of the storage system of thisinvention after erection and prior to introduction of granular material;

FIG. 9 is a pictorial illustration of a filling spout;

FIG. 10 is a diagrammatic illustration showing the movement of a coverduring growth of a pile of granular material;

FIG. 11 is a side elevation view of a storage system in accordance withan alternative embodiment of the invention;

FIG. 12 is a horizontal plan view of the storage system of FIG. 11; and

FIG. 13 illustrates means for securing a cover section to a retainingwall.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A typical storage system for storage of about 500,000 bushels of corn isillustrated in the side elevation view of FIG. 1. As shown therein, apile of corn 20 is covered by a flexible cover 21 comprising a pluralityof cover sections 22. One of the cover sections 22 is partially cut awayto illustrate the pile of corn 20. In the illustrated embodiment cover21 comprises eight triangular cover sections 22 as best illustrated inFIG. 2. Cover sections 22 may each have a length of about 80 ft. attheir base and a length of about 105 ft. along the edges which extendinwardly therefrom. Cover sections 22 are preferably fabricated fromnylon reinforced vinyl having a weight of about 18 ounces per squareyard. Accordingly, each of cover sections 22 weighs about 400 lbs. Coversections 22 are joined along a series of seams 23 as hereinafterdescribed.

The pile of corn 20, with cover 21 stretched conformable thereacrossrests upon a support surface 25 and extends theretoward at an angle ofrepose of about 22° from the horizontal. Support surface 25 may comprisea 5 inch thick layer of conventional blacktop, but other surfaces aresatisfactory. It is preferred that support surface 25 be impervious.Preferably a 5 ft. retaining wall 24 retains the pile of grain at itsbase.

The retaining wall 24 is air permeable for aeration of the grain ashereinafter described. Such aeration is facilitated by an aeration tower26 which is air permeable and which extends upward through the pile ofgrain from support surface 25 to the peak 29 of the pile 20. An aerationfan or fans 30 (FIG. 9) of conventional design and capable of movingabout 12,500 to 50,000 cubic ft. of air per minute may be mounted at thetop of aeration tower 26. When fan 30 is activated it produces a flow ofair from retaining wall 24 through the grain pile 20, into aerationtower 26 and upwardly into the atmosphere. As hereinafter described indetail, aeration tower 26 supports cover 21 prior to the introduction ofgrain. If aeration is not required, then aeration tower 26 may bereplaced by a post or any other means capable of providing temporaryvertical support.

Cover sections 22 are joined to a lifting ring 43, which surroundaeration tower 26 at peak 29. A power supply for fan 30 may extendupwardly through aeration tower 26, or alternatively, up an elevator 28and thence outwardly along a loading conveyor 27. Elevator 28 andconveyor 27 are used for supplying grain to a funnel positioned inaeration tower 26, as best illustrated in FIG. 9.

For ease in unloading grain from the pile 20 there is an unload conveyor31 in support surface 25, as illustrated in FIG. 3. Approximately 25% ofpile will flow under gravity into conveyor 31. The remainder may beunloaded by using a front loader to push grain into the conveyor. Inorder to provide access to the conveyor 31 for unloading, retaining wall24 has a removable section 32. Prior to unloading, one of the seams 23is unfastened and a pair of cover sections 22 are folded backwardly toexpose a portion of pile 20 in the area of wall section 32. Preferably,unload conveyor 31 is a screw type conveyor and is provided with a coverscreen 33.

Retaining wall 24 may be supported by a series of steel support braces34 as best illustrated in FIG. 4. Support braces 34 are covered byretaining plates 35, which may be fabricated from 20 gauge perforatedgalvanized steel. Retaining plates 35 may be backed by supporting ribs36.

The system is made ready for storage of grain by spreading the coversections 22 out on support surface 25. Cover sections 22 are initiallyfolded up and stored on pallets of suitable size. The pallets may betransported to the work site and the cover sections spread out by handas illustrated in FIG. 5. After being spread out, cover sections 22 arejoined to form seams 23, as best illustrated in FIGS. 6(a) and 6(b). Aseam 23 is assembled by bringing together mating portions of two coversections 22(a) and 22(b), as illustrated. Cover section 22(a) has anupwardly folded marginal edge 37(a) and a downwardly extending flap 38which depends therefrom. Cover section 22(b) has a marginal edge 37(b),which extends upwardly between marginal edge 37(a) and flap 38. Marginaledges 37(a) and 37(b) and flap 38 are provided with a series of grommets39, which are aligned to define apertures for entry of a first lacingline 40. Lacing line 40 is looped through the aligned grommets 39 andthereafter captured by a second lacing line 41. Lacing lines 40 and 41preferably are 3/8 inch polypropylene rope. Preferably, margins 37(a)and 37(b) and flap 38 are all reinforced with four inch wide webmaterial.

After cover sections 22 have been laced together they are attached tolifting ring 43 as illustrated in FIG. 7. Lifting ring 43 may becomprised of two sections which may be joined to fit around aerationtower 26. Cover sections 22 are provided with a series of loops 48,which are passed over lifting ring 43 before the sections thereof arejoined. A pair of cables 42 (one of which is visible in FIG. 7) areattached to opposite sides of lifting ring 43, and the lifting ring withthe attached cover sections 22 is lifted by a winch (not illustrated).Lifting is continued until the lifting ring has been lifted to apredetermined fill height as illustrated in FIG. 8. The predeterminedfill height corresponds to the peak of the pile of grain which will beerected under the cover. In the illustrated embodiment that height maybe about 41 ft. Due to the natural tendency of the cover to sag underthe force of its own weight, the perimeter of the cover pulls inwardlyaway from retaining wall 24, as shown in FIG. 8. A series of guy wires49 may be attached to aeration tower 26 for supporting the structure ofthis stage.

After cover 21 has been raised to the predetermined height, as describedabove, the grain loading operation commences. For this purpose a funnel44 is mounted in the top of aeration tower 26, as illustrated in FIG. 9.Grain which is introduced into funnel 44 exits through four spouts 46which reach out to the four sides of aeration tower 26 at a point belowthe final position of lifting ring 43. Funnel 44 is positioned forreception of grain from loading conveyor 27. For the illustrated 500,000bushel system, loading progresses at the rate of about 8,000 bushels perhour.

FIG. 10 illustrates the movement of cover 21 during the course of thefilling operation. During the initial stages of filling the pile ofgrain 20 builds up to the point where it comes into contact with cover21, as shown in solid lines in FIG. 10. At this point, cover 21 is drawninwardly from retaining wall 24, as discussed above.

As the grain moves into contact with cover 21 it flows thereunder andbegins lifting the cover upwardly. Concomitantly with this upwardlifting the frictional force of the flowing grain carries the coveroutwardly. Thus when the grain has built up to an intermediate point asindicated by the reference numeral 47, cover 21 sags downwardly to thepile of grain and thereafter rests partially on the pile and partiallyon support surface 25. The filling is continued until the grain reachesthe pouring point and defines a pile extending along its normal angle ofrepose in an outward and downward direction. At the point the pile has aconfiguration as indicated reference numeral 48. By then cover 21 hasbeen carried upwardly and outwardly to stretch conformably over the pilefrom peak 29 to the wall 24. Cover 21 is pulled over the top of wall 24and tied down by a tie line 45 as illustrated in FIG. 13. The grain isthen fully stored.

An alternative embodiment of the storage system of this invention isillustrated in FIGS. 11 and 12. The system of FIGS. 11 and 12 is erectedand filled as described above for the embodiment of FIGS. 1 and 2. Inits alternative embodiment the system may have a racetrack configurationas viewed from above. In the alternative embodiment there are aplurality of aeration towers 50 surrounded by an elongated opening 52 incover 53. Cover 53 comprises a series of cover sections 54, which arereleasably joined together as described above. The perimeter of cover 53is releasably secured to retaining wall 51. An overhead conveyor 55 isprovided for delivering grain to funnels mounted at a proper pouringheight within each of aeration towers 50.

It will be appreciated that a storage system in accordance with thepresent invention may be used for storage of any flowable granularmaterial, such as salt, potash, pelletized material or even coal, inaddition to various types of grains. The system is especially clean inthat all dust generated by the filling operation is confined under thecover. Furthermore, while the system as designed for temporary storage,it is quite suitable for storing granular materials for extended periodsof time. The system is much less expensive than conventional storagesystems and requires little maintenance except for replacement of thecover. The average life of a typical cover is about ten years. Thesystem is suitable for storing granular material in piles as small asabout 5,000 bushels but is particularly advantageous for storage oflarger piles from about 25,000 bushels up to about 3,000,000 bushels.

While the method herein described, and the form of apparatus forcarrying this method into effect, constitute preferred embodiments ofthe invention, it is to be understood that the invention is not limitedto this precise method and form of apparatus, and that changes may bemade in either without departing from the scope of the invention.

What is claimed is:
 1. A system for creating and storing a conicallyshaped pile of flowable granular material extending downwardly from apredetermined height along a natural angle of repose comprising:asupport surface for said pile; vertical support means extending upwardlyfrom said support surface for a distance at least as great as saidpredetermined height; a plurality of flexible, generally triangularcover sections suspended at their apices from a point on said verticalsupport means at said predetermined height; and means for introducingsaid granular material through said point of suspension and under saidcover sections;said cover sections being marginally joined along thoseof their sides which radiate outwardly from their apices with theirremaining sides being free for movement with said granular materialduring introduction thereof; said cover sections being configured suchthat they collectively conform to the surface of said pile when fullycreated.
 2. A system according to claim 1 wherein said cover sectionsare joined together at releasably laced seams.
 3. A storage systemaccording to claim 2 wherein at least some of said seams comprise amarginal edge of one cover section gripped between a marginal edge and adepending flap of an adjacent, mating cover section, and a lacingmaterial laced therethrough.
 4. A storage facility according to claim 3wherein the mating marginal edges of said cover sections and saiddepending flaps are provided with grommets which are lined up to definelacing apertures.
 5. A storage system according to claim 2 wherein saidsupport surface is impervious.
 6. A storage system according to claim 5and further comprising an unloading conveyor mounted on said supportsurface under said pile.
 7. A system according to claim 5 and furthercomprising a retaining wall surrounding said support surface.